The present invention relates to a semiconductor memory device, and more particularly, to a double data rate (DDR) synchronous dynamic random access memory (SDRAM) having a write-interrupt-write function.
DDR SDRAM semiconductor devices each have a write-interrupt-write function. In a DDR SDRAM, data to be written is input from the outside through one group of input/output lines to a memory block. The write-interrupt-write function refers to when the writing of data is interrupted for the writing of data input through another group of input/output lines to the memory block.
In the DDR SDRAM semiconductor device, a period of two clock cycles of an external clock signal is taken to externally input data loaded onto the groups of input/output lines. However, in a conventional DDR SDRAM semiconductor, such a data loading timing is not considered in performing the write-interrupt-write function, with the result that a mis-operation may occur in the DDR SDRAM memory device.